Opalescent Nudibranch

Hermissenda crassicornis

Opalescent nudibranch are a species of ‘sea slugs’, they have rhinophores that are projections which look like horns on their head. These rhinophores help them to find food by sensing the chemicals in the water.


Opalescent nudibranch are small, typically around 25 mm (less than an inch) they can however, grow to 70 mm (2.7 inches). They always have bright orange areas on their back, and a faint blue line across the side of their body. The nudibranch has cerrata or finger like projections on their back which act as gills and their shape gives the nudibranch more surface area, therefore more intake of gases. Their distinctive colouration also acts as a warning to potential predators…

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